fix #949 extraTransaction().setCustomAnimations() exitAnimation is not working

Author: YoKeyword

fragmentation_core/src/main/java/me/yokeyword/fragmentation/SupportFragmentDelegate.java

@@ -329,6 +329,9 @@ public FragmentAnimator getFragmentAnimator() {
                 mFragmentAnimator = mSupport.getFragmentAnimator();
             }
         }
+        if (mCustomExitAnim != Integer.MIN_VALUE) {
+            mFragmentAnimator.setExit(mCustomExitAnim);
+        }
         return mFragmentAnimator;
     }